Size-structure and growth of individuals suggest high exploitation rates in the fishery for blacklip abalone, Haliotis rubra, in New South Wales, Australia

Abstract

The proportion of recent recruits in the catch of the NSW abalone fishery was estimated by combining information on growth rate and the size-structure of the commercial catch. Growth rates of individuals around the minimum length limit of 115 mm suggest most individuals less than 125 mm recruited to the fishery in the last year. These individuals make up between 50% and 95% of the commercial catch in all zones of the fishery. This dominance of recent recruits in the catch of the fishery makes monitoring of the abundance of pre-recruits, to provide information on likely fluctuations in recruitment, particularly important to management. Growth rates of individuals below the minimum length limit of 115 mm suggest most individuals above 100 mm will recruit to the fishery in the next year. Monitoring over the last four years has found no significant decline in the relative abundance of these pre-recruits in six major regions of the fishery. The high exploitation rate, suggested by the combination of patterns in growth and the proportion of recruits in the catch, combines with several other factors to make the NSW abalone fishery very different from those for the same species in other states in Australia.